This invention relates to an Alaskan offshore drilling base from which oil and gas wells may be drilled. Difficulties are encountered in building any type of an offshore base due to the rough terrain, cold weather, and lack of manufacturing facilities. It is extremely difficult to build a steel offshore platform and transport it to a location offshore the North Slope of Alaska. Ice islands have been suggested but man-made islands in shallow water locations have been found to be the most practical.
The construction of man-made islands in shallow water locations is made difficult by the lack of materials that may be used. It is impractical to make an island out of concrete due to the lack of any adequate supply of cement. The cost and difficulty of transporting large quantities of cement hundreds or thousands of miles at the severe temperatures encountered in Alaska rule out cement as an island-building material. To date, the greatest success has been encountered in building man-made islands or artificial drilling bases out of sand and gravel which is readily available. Thus, sand and gravel drilling islands have been constructed by barging the material on shallow barges to the offshore location at which the island is to be built. There, the sand and gravel mixture is deposited at the selected location and the barging operation is continued until an island of suitable size has been constructed.
Alternatively, an island for drilling operations may be constructed during winter weather by trucking sand and gravel from shore to the offshore location. Generally, water is sprayed on the road over the ice so as to build up the thickness of the ice to about ten feet so as to support the weight of large trucks carrying 30 to 40 cubic yards of sand and gravel. The trucks dump the sand and gravel at a selected location where a hole has been drilled in the ice and a bulldozer pushes the sand and gravel through the hole until an island is built up below the ice. When the island is finally built up and fills the hole, the ice is cut out and the hole enlarged until the top of the island has been extended to the desired diameter, say, 200 to 500 feet. Also, the island is built up to a height of 15 to 35 feet above the high water level, depending upon the height of the waves and the severity of the storms that may be anticipated. Sufficient additional sand and gravel are added to the size of the island until the desired angle of the sloping sides of the island has been achieved. The sloping sides of the island are then preferably smoothed down in any suitable manner well known to the construction trade.